Wash arm for a dishwasher



FIG. 1 is a perspective view of a wash arm for a dishwasher showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof; and

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a wash arm for a dishwasher, as shown and described. 